The hearing is part of an inquiry by the California Public Utilities Commission.

Customers in the San Diego, Riverside and Orange County regions pay about $64 million dollars a month to run San Onofre. Majority owner Southern California Edison shuttered the plant early last year after equipment problems caused a tiny radiation leak. Federal regulators say there were flaws in how the equipment manufacturer -- Mitsubishi Heavy Industries - conducted tests. Joe Como, acting director of the Division of Ratepayer Advocates within the California Public Utilities Commission, said the concept of accountability dictates that ratepayers no longer pay the costs for San Onofre.

"Whoever's responsibility it is, whether it's Mitsubishi or Edison or both, that's their business," Como said. "But right now, the customers are footing the bill for all of it and that we find to be very unjust."

In a statement, Edison said it will continue to look to warranties and insurance to recover costs associated with the current outages. Como said payments for San Onofre should have been removed from customer bills soon after the plant was shut down. But state regulators did not initiate an investigation into whether that should happen until October. Meanwhile, Edison wants to restart one of its reactors at reduced power which could involve more ratepayer expense.